Field of the Invention
The present invention relates to an image processing apparatus which performs image restoration processing on a captured image.
Description of the Related Art
For an object captured via an image pickup optical system, light emitted from one point cannot be converged to another point and has a minute spread due to an influence of a diffraction, an aberration, or the like that occurs in the image pickup optical system. Such a minutely-spread distribution is referred to as a PSF (point spread function). Due to the influence of the image pickup optical system, the captured image is formed with the PSF convolved with the image, and accordingly, the image is blurred and its resolution is deteriorated.
Recently, the captured image is typically stored as electronic data, and a method (image restoration processing) has been proposed which corrects an image deterioration caused by the image pickup optical system by performing image processing.
Japanese Patent Laid-open No. 2012-65187 discloses an EDOF technology in which a wavefront modulation element is inserted into an image pickup optical system to enlarge a depth of focus and to uniformize optical characteristics in an image, and thus image restoration processing is performed to improve the quality of the image. According to the method disclosed in Japanese Patent Laid-open No. 2012-65187, the optical characteristics are uniformized for various image capturing conditions, and thus a process of generating an image restoration filter is simplified and the processing speed can be improved.
However, in order to use the EDOF technology disclosed in Japanese Patent Laid-open No. 2012-65187, it is necessary to insert the wavefront modulation element in the image pickup optical system. Therefore, in the method disclosed in Japanese Patent Laid-open No. 2012-65187, the speed of the image restoration processing cannot be improved by using a typical image pickup apparatus.